Private browsing is a way of using your web browser such that it doesn't leave a trace on the computer of any of the sites you visited. While this isn't an effective way to be anonymous on the Internet (see Private Browsing Myths), it's often helpful if you want to see what your website looks like to anonymous visitors.
To enable private browsing, please find your web browser below and click the link - or use the keyboard shortcut provided.
Firefox (Ctrl-Shift-P on Windows, Command-Option-P on Mac)
Chrome (Ctrl-Shift-N on Windows, Command-Shift-N on Mac)
Safari (Command-Shift-N on Mac)
Internet Explorer (Ctrl-Shift-P)
Sigh - I couldn't find this page beforehand when I looked, but I just found this: http://www.wikihow.com/Activate-Incognito-Mode